COMPATIBILITY_LEVEL Is the version of SQL Server with which the database is to be made compatible. The value must be one of the following:
80 = SQL Server 2000
90 = SQL Server 2005
100 = SQL Server 2008

Compound Operators:
Operators that perform an operation and set a variable to the result, for example SET @x += 2, are available.

The GROUPING SETS, ROLLUP, and CUBE operators are added to the GROUP BY clause. There is a new function, GROUPING_ID(), that returns more grouping-level information than the existing GROUPING() function. The non-ISO compliant WITH ROLLUP, WITH CUBE, and ALL syntax is deprecated.

This new Transact-SQL statement performs INSERT, UPDATE, or DELETE operations on a target table based on the results of a join with a source table. The syntax allows you to join a data source with a target table or view, and then perform multiple actions based on the results of that join.

SQL Server 2008 introduces a new catalog view and system functions to provide consistent and reliable SQL dependency reporting. You can use sys.sql_expression_dependencies, sys.dm_sql_referencing_entities, and sys.dm_sql_referenced_entities to report on cross-server, cross-database, and database SQL dependencies for both schema-bound and non-schema-bound objects.

Table-Valued Parameters:

The Database Engine introduces a new parameter type that can reference user-defined table types. Table-valued parameters can send multiple rows of data to a SQL Server statement or routine (such as a stored procedure or function) without creating a temporary table.

Max number of tables or any other object cannot exceed the limit of max number of all objects in a database.

As per MSBOL: Database objects include objects such as tables, views, stored procedures, user-defined functions, triggers, rules, defaults, and constraints. The sum of the number of all objects in a database cannot exceed 2,147,483,647.